Gotcha.
My experience, and those of many others I know including pro riders is that non-round rings hurt top sprint power. Very hard for me to prove, but, a lifetime of riding and training with power since PowerTap first came out (wired) and using rotor q’s for years, I finally moved off the q’s for round rings a couple years ago. Sprint power “seems” to have improved slightly. Again I can’t prove it as it could be something else. Certainly, to me, what’s way more important is how you get up to peak power. So maybe it’t the “snap” that is better with the round rings. The only thing I’m blessed with is neuromuscular ability. I can snap with the best of them so, I feel pretty confident in what I’m feeling and observing.
As far as speed goes, as you’ve indicated, that could be due to so many variables that saying rings added 1 mph is just not true. Not trying to be mean or harsh and again I can’t prove that. But, from experience, just not even close.
All this said I should add I really really wanted these things to due exactly the manufacturer says they do: more power at a lower HR. Unfortunately I’ve just not found either and am left thinking non-round rings are just more snake oil.